Thrombpoietin ia the only physiological relevant hematopoietic growth factor that regulates platelet production. Since its identification three years ago, extensive research was undertaken by the original, primarily industrial-based, laboratories in an effort to understand its mechanism of action. Much of this information was summarized at the Keystone Conference on Thrombopoietin and Cytokine Regulation of Platelet Production held in February of 1996. In the past several years a large number of new academic and industrial investigators have entered this field and have greatly extended the scope of basic scientific investigation on thrombopoietin. In addition, the clinical development of this area is progressing so rapidly that a large number of studies are about to be reported..It is therefore the purpose of this Keystone Symposium on Molecular Regulation of Platelet Production to bring together the academic and industrial researchers in this area to discuss the recent basic and clinical findings in this rapidly progressing area. Given the expectation that one or more of the recombinant thrombopoietin molecules will be approved by the FDA within the next year, The timing of this gathering is crucial. This symposium will allow new clinical and basic science investigators to exchange their findings at a time when the clinical applications of thrombopoietin are being developed. Guidelines for the use of thrombopoietin will emerge which will ensure the rationale use of these molecules in the clinic. Young investigators and trainees will have access to the most recent clinical and basic information with which to formulate their own experiments. Established clinicians and basic scientists will have a unique opportunity to synthesize current information and guide the further development of thrombopoietin. The provision of adequate resources to fund this symposium will guarantee an equitable balance of viewpoint between academic and industrial researchers as well as the opportunity for academically-based post-doctoral and graduate students to participate.